Reciprocating mechanism and system of motor control therefor.



W. FOSTER.

RECIPRUCATING MECHANISM AND SYSTEM or MOTOR CONTROL THEREFOR.

APPLICATION FILED [EB-1|. 19I3- RENEWED MAR. 19, I911- 7 1,252,897.Patented Jan. 8,1918."

UNITE STATES PATENT OFFICE.

warm rosrna, or rnamrmrn, new masar, assrenoa 'ro mnns-Bnunnr-ronn comm,or new your, a. 1. a ooaroaarron or new JERSEY.

BECHQROCATING MECHANISM AND SYSTEM 0! MOTOR GONIRlJL THEREFOR.

Specification of Letters Patent.

Patent ed an. 8, 1918.

' Application filed- Icbra'ary 11, 1918, Serial No. 747341. Renewedlarch 18, 1817. Serial No. 155,841.

To all whom it may concern:

Be it known that I, WALTER Fos'rna, a a citizen of the United States,residin at Plainfield, in the county of Union and tate of New Jersey,have invented certain new and useful Improvements in ReciprocatingMechanism and Systems of Motor Control 'Therefor, of which the followingis a full,-

clear, and exact description, such as will enable 'others skilled in theart to which it appertains to make and use the same.

The invention relates to mechanisms having reciprocating tables andreversing motors connected with the tables to drive them.

One of theobjects of theinvention is to provide amechanism of this,class having improved means for eifectingthe dynamic braking of themotor automatically upon the operation of a circuit breaker.

A further object of the invention is the provision of an eflicientsystem of control in which many .of the dangers attendant upon the useof motor-operated machines are eliminated. I 7

Another object is the provision of reliable means for stopping a motorquickly and independently of any external power.

Another object is the provision in a motor control of a. simple,inexpensive and durable braking device.

Another object is the provision of an automatic brake which iscompensated to:

the proper extent for certain variations in the speed of the motor atthe time the brake is applied.

Other objectswill be in part obvious, and

in part pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements and arrangement of parts which will beexemplified in the construction hereinafter set forth, and the scope ofthe application of which vwill be indicated in the following claims.

In the drawings, in which are illustrated one or more of variouspossible embodiments of the several features of the invention, a

Figure 1 represents diagrammatically a system of motor control wherein,among other things, the shunt. field is adapted to be short-circuitedupon itself;

Fig. 2. illustrates diagrammatically another system of motor control inwhich the dynamic current from the armature may be caused to passthrough the shunt field and Fig. 3 is a conventional representation of amachine of the kindwith which or as a part of which my improved systemof motor control is primarily adapted to be used.

Similar reference characters refer to similar parts throughout bothviews of the draw 2 Referring now to the apparatus illustrated in Fig.1, there is shown at 1 a motor comprising an armature 2, a shunt field3, one or more interpole windings 4 and a second winding 5 for emergencyuse, hereinafter referred to as the auxiliar 1 field winding. The latterwinding, which consists of a few turns of comparatively heavy wire,- maycomprise part or all of theseries turns provided with an'ordinarycompound motor: or the winding 5 may be laid over the field coils. of anordinarv shunt motor; or partof this auxiliary winding 5. may be used inthe regular service of the motor as a series field, aiding or opposingthe shunt field. However in order to avoid encumbering the patent withthe description of a large number of. possible embodiments of this andother features of the invention, the illustration has been confined to a'motor which in ordinary operation runs without.

ating solenoids 17 18 controlled by the pilotswitch 19.. These switches'15, 16,19 and solenoids 17, 18 illustrate conventionally a servicecontroller adapted,'upon a manual or automatic shifting of a pilotswitch, to reverse the direction of current throughthe armature 2 andsimultaneously change the speed of the motor as by increasing ordecreasing the value of the resistance in series with the shunt field 3.In practice the servmachine armature 2; and from-the ice controller maybe of any approved type, manually or automatically operated, for areversing or non-reversing motor, and wlth or without adynamic or otherbraking device. The controller, however, preferably takes the form setforth in the patent to Samuel H. Keefer, No. 1,003,269, granted Setember 12, 1911.

n various types of apparatus where it 15 important that thedrivenelement should not travel beyond a predetermined point or points,there has been need of an economical, reliable, and eflicient means forbringing the driven element quickly to a stop without undue strainsof anelectrical or mechanical nature, upon a failure of external power at themotor from any one of a number of causes. Such means is provided in theillustrated embodiment of the present invention as follows: Inmechanical or electrical connection with the movable elements 20, 21 ofthe circuit breaker 10 which opens upon an overload or a failure ofexternal power is a movable switch blade or other device 22 adapted tocontact simultaneously, or preferabl v as illustrated, successively as astepswitcli, with the stationary members 23, 24, 25. The blade 22 andthe stationary memb ers.23', 24, 25 may be connected in a variety ofways with the several parts of the motor. The connections illustrated byway of example am, from the blade 22 to one side of the shunt field 3;from the first member 23 to the other side of the shunt field 3; fromthev second member 24 to one side of the. 4 third stationary member 25to the other side of the armature 2 through an ohmic resistance 26, theauxiliary winding 5 and the interpole winding 4. The resistance 26.. isso proportioned as to limit the maximum emergency braking currentthrough the armature 2, interpole winding 4 and auxiliary winding 5, toa safe value and thus avoid excessive electrical or mechanical shocks tothe apparatus. The

inclusion of some or all of the interpole' windings in this emergencybraking circuit insures good commutation for the dynamic current.

In Fi which t therefor shown in Fig. 1 may be used. The comprises areciprocating table A which is suitably connected with the motor 1 to bedriven thereby. Secured to the table are devices such as the dogs. B andC adapted to engage the pilot switch 19 and move it first in onedirection and then in the other direction as the table reciprocates. Inthis way the motor is, caused to periodically reverse.

If the driven element is a reciprocating table such as that illustratedat A or if for some other reason. the motor is in service required torun first in a forward direction 3 I have shown a machine with e motorand system, of control I mg 5 and an ohmic resistance 26.

and then in a reverse direction it is often desirable to have, for examIe, the return stroke made at a higher s than the forward stroke, andthe usual method of var ing the s eed of the motor is by having t eshunt fie d current stron er on the forward stroke. In such a case ifthe braking action were sufiiciently powerful on the' return stroke thecollapse of the greater flux when the shunt field was short-circuitedduring the forward stroke would be liable to injure or break thegearing; in other words, the flux due to the shunt field on the forwardstroke would be too great. Now it will be noticed that in theillustrated embodiment of the present invention the current in theauxiliary winding 5 flows in one direction if the circuit breaker 10opens While the motor is on one stroke and flows in the oppositedirection if the motor is rotatin in the opposite direction when thecircuit ireaker 10 opens; and by connecting the windings so that on theslower stroke the auxiliary winding 5 is energized will oppose the shuntfield 3, this -auxiliary winding 5 will if energized on the fasterstroke aid the shunt field 3 and thereby cause the braking'effect to becompensated for the difference in speed of the motor on the two strokes.

In Fig. 2, the shunt field 3 instead of being short-circuited uponitself on the opening of the circuit-breaker 10 is at such a timeenergized by dynamic current from the rotating armature 2. This may beaccomplished by making the movable switch blade 27, attached to the mainswitch elements 20, 21 of the circuit-breaker, of two relativelyinsulated sections 28, 29 adapted to make contact with the stationarymembers 30, 31, and 32, 33, respectively. The uppermost and lowermoststationary members 30, 33 are shown as connected to the two sides of theshunt field 3 and the other members, 31,

in Fig. 1 comprises a motor 1, controller for regular service,circuit-breaker 10 with overload and no-voltage release, and means forbraking the motor 1 upon a failure of ex ternal power at themotor; Atsuch a time the circuit-breaker 10 opens, thereby shortfield '3 andclosing a;

circuiting the shunt series circuit containing the armature 2, interpolewinding 4, an auxiliaryfield wind- If the motor is required to'run in.two directions at difl'erent speeds with a variable-field method ofspeedregulation, the braking effect of the auxiliary winding 5 added to thatthe nausea shunt field on the faster strokeand sulr tracted from the.efiectof the shunt field on the slower stroke com ensates for the in- 2aa be said to fall therebetween.

claimas new and desire equality in braking e ciency due to theshort-circuitin of a weaker shunt field on the faster stro e. In Fig. 2the shunt-field is not short-circuited upon itself, but is energizedduring the emergency braking operation by dynamic current from thearmature 2.

Asmany changes could be made in the above construction and many aparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense. a

It isalso to be understood that the langua e used in the followingclaims is inten ed to cover all of the generic andspecific features ofthe invention herein described and all statements of the scope'of theinvention, which, as a matter of language, might Having described myinvention, what I Patent is: I

1. The combination of a reciprocating table, a reversin electric motorfor driving the table, atab e operated switch for controlling the motorto periodically reverse it, and means automatically operable upon thefailure of external power for dynamically braking the motor and forcausing the power of the braking action to be greater for one directionof motor rotation than for the other. u

2. The combination of a reciprocating table, a reversing electric motorfor driving the table, a table operated switch for controlling themotorto periodically reverse it and cause it to run faster in one directionthan in the" other, and means automatically operable upon the failure ofexternal power for dynamically braking the motor and for causing thebraking action to be greater for rotation at the faster speed than forthe rotation at the slower speed.

reaker for dynamically braking the motorand for causing the brakingaction to be greater for one direction of motor rotation than for theother. a

4. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external power, means adapted upon afailure of external wer to brake the motor, and means where y the tosecure by Letters brakin force is compensated for the direc tion 0rotation of the motor at the time the brake is applied. a

5 In a system 'of motor control, in combination, a motor, meansconnecting the motor to a source of external power means adapted upon afailure of external power to brake the motor, and means whereby thebraking force is compensated .for the speed of the motor at the time thebrake is applied.

6. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external power, means adapted upon a'failure of external power to brake the motor, and means whereb thebraking force is compensated for the irection of rotation of the motorat the time the brake is applied.

7. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external ower, and means adaptedupon a failure 0 external power to short-circuit a field winding of themotor.

8. In a system of motor control, in combination, means connecting themotor to a source of external power, means adapted upon a failure ofexternal power tobrake the motor, andmeans whereby the braking flux iscompensated for the speed of the motor at the time the braking isapplied.

9. In a system "of motor control, in combination, a motor, meansconnecting'the motor to a source of external power, and means adaptedupon a failure of external power to short-circuit a field winding of themotor and to close a circuit comprising the'armature.

10. In a system of motor control, in com- 11. In a system of motorcontrol, in combination, a motor, means connecting the motor to a sourceof external power, and means adapted upon a failure of external power toshortcircuit a field winding of the motor and toiclose a circuitcomprising the armature and another field winding.

12. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external power, and means adaptedupon a failure of external power.

to short-circuit a field winding of the motor and to close a circuitcomprising thearmature, an interpole winding and another field winding.i

13. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external power, and means adaptedupon a failure of externalpower i to short-circuit a field winding ofthe motor and to close a circuit comprising the armature,. an interpolewinding, another field windin and a'resistance.

14. n a system of motor control, in combination, a motor, meansconnecting the motorto a source of external power, means ada ted upon afailure of external power to s ort-circuit a field winding of the motor,and means whereby the flux due to the 'shortcircuiting of said windingis increased or diminished b a second flux, accordingto the speedof t emotor at the time the power fails. a

15. In a system of motor control, in combination, a motor, meansconnecting the motor to a sourceof external power, means adapted upon afailure of external power to short-circuit a field winding of the motor,and means whereby the flux due to the shortcircuit of said winding isincreased or di minished by a second flux,- according to the directionof rotation of the motor at the time the power fails.

16. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external power, and means adaptedupon a failure of external power to short-circuit a field winding andthereafter to close a circuit comprising the armature.

17. In a system of motor control, in com-,

bination, a .motor, means connecting the motor to a source of externalpower, and means, adapted upona failure of external power toshort-circuit a field winding and thereafter to close a. circuitcomprising the armature and an interpole winding.

18. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external power, and meansadapted'upona' failure of external power .to short-circuit a fieldwinding and thereafter to close a circuit comprising the armature andanother field winding.

19. In a. system of motor control, in com-' bination, a motor, meansconnecting the motor to a source of external power, and

means ada ted upon a'failure of external power to s ort-circuit a? fieldwinding and thereafter to close a circuit comprising the armature, aninterpole winding and another field winding. I

20. In a system of motor control, in combination, a motor, meansconnecting the motor to a source of external power, and

means adapted upon a failure of external power to short-circuit a fieldwinding and,

thereafter to close a circuit comprising the armature, an mterpolewinding, another field winding and a resistance.

21. In a system of motor control, in com- 7 bmatlon, a motor, acircuit'breaker provided with a no-voltage and amoyeril'oad release, anda step-switch operated 'u on the opening of said circuit breaker' 'fo'rshort circuiting a field winding of the motor and thereafter closing acircuit comprisingthe armature of the motor.

22. In a system of motor control, in combination, a motor, and meansadapted upon a failure of external powerto short circuit a field windingof .the motor and "thereafter close a circuit comprising the armature,said means comprising a circuit'breaker and a step-switch adapted to beclosed upon the opening of said circuit-breaker.

23. In a system of motor control, in com-, bination, a motor, and meansadapted upon a failure of external power to short-circuit a fieldwinding of the motor and thereafter close a circuit comprising thearmature and;

an interpole winding, said means comprising a circuit-breaker and astep-switch adapted to be closed upon the opening of saidcircuit-breaker.

24. Ina system ofmotor control, in combination, a motor, and meansadapted upon a failure of external power to short-circuit a fieldwinding of the motor and thereafter close a circuit comprising thearmature and another field winding, said means compris-' ing acircuit-breaker and a step-switch adapted to be closed upon the openingof said circuit-breaker. t p

25. In a system of motor control, in combination, a motor, and meansadapted upon a failure of external power to short-circuit a fieldwinding of the motor and thereafter 1 close a circuit comprising thearmature, an interpole winding and another field WlIldmg, sald meanscomprising a clrcult-breaker anda step-switch adapted to be closed uponthe opening of said circuit-breaker;

26. In a system of motor control, in com-- bination, a motor, and meansadapted upon a failure of external power to short-circuit a fieldwinding of the motor and thereafter close a circuit comprising thearmature, an interpole winding, another field winding and a resistance,said means comprising a'clrcuitbreaker and a step-switch adapted to beclosed upon the opening of said circuitbreaker.

In testimony whereof I afiix my signature,

in the presence of two witnesses.

WALTER FOSTER. Witnesses: GEORGE E. Gnasxnmr, J. T. MACMURRAY.

